When a fuel cell vehicle works, the hydrogen as a fuel has a chemical reaction with the atmospheric oxygen in the fuel cell on board the vehicle to generate electric power to start the motor and drive the vehicle; in addition to electricity, the chemical reaction of this category only generates water, therefore, fuel cell vehicles are called “real environmentally friend vehicle”. Besides, the energy conversion efficiency of a fuel cell is 2˜3 times higher than an internal combustion engine. Therefore, fuel cell vehicle is ideal in respect of both energy utilization and environmental protection.
In recent years, fuel cell vehicle has made a more important progress. Such world-renowned auto-makers as Daimler Chrysler, Ford, Toyota and General Motors Corporation have entered into the fuel cell vehicle manufacturing field one after another; as a result, the technology of fuel cell on board vehicle has had a remarkable advancement.
In view of many advantages of fuel cell over internal combustion engine, engineers have tried to apply fuel cells in multiple means of transportation for energy supply, however, a pity is that such application has only succeeded in such large vehicles as car, bus, etc. but in such small vehicles as forklift, etc., there has been almost no rational scheme.
Through retrieving existing open literatures, an invention patent of China called “a kind of energy mixed type power system for fuel cell vehicle” with application number “200610011555.1” has the following problems:
1. In addition to a battery pack supplying power to the power system, an additionally configured 24V battery is needed for starting. To charge the 24V battery, a 24 VDC/DC converter is additionally provided; as a result, the system has a lot of parts and possible failure points and at the same time, there are many lines that the parts correspond to, which occupy a lot of space, and the system volume can not be reduced.
2. The controller for a whole vehicle is always connected to the 24V battery and through the 24V battery, the power it needs is supplied; therefore, the controller for a whole vehicle is always in a running condition, as a result, the energy consumption of the system is high.
3. The controller for a whole vehicle controls through a key signal the supply of power by the high-power relay K2 to the fuel cell auxiliary system, starts the fuel cell; after starting, switches to supply of power by the high-power relay K1 to the fuel cell auxiliary equipment through the fuel cell; too many relays result in system being trivial and the volume being unable to be reduced.
4. Adopt scattered fuel cell controller, whole vehicle controller, battery energy management system; each device needs an enclosure protection and this causes a big volume; the devices needs lines to connect between them, resulting in a lot of harnesses; all these are not favorable to a compact system volume.
5. The fuel cell auxiliary system gets electricity from the fuel cell directly. As the voltage fluctuation range of fuel cell is large, a customized controller or power supply is needed to supply power to the auxiliary system; this will cause the system to have a high cost.
When adopting a similar trivial system in the above patent to design a forklift fuel cell system, the designed system will require redesign of forklift. For example, such two patent literatures as the American patent literature called “FUEL CELL INDUSTRIAL VEHICLE” with publication number “US2009236182A1” and the Canadian patent literature called “FUEL CELL INDUSTRIAL VEHICLE” with publication number “CA2659135A1” have publicized design schemes requiring re-manufacturing of forklift, as the lead-acid battery can not be replaced directly without modifying a forklift system.
Besides, the fuel cell system design that can be put directly in a forklift in the existing technology is bulky and miscellaneous. Feedback from users shows a high failure rate and it is troublesome to maintain. Around parts and components, there is no space for disassembly, maintenance operation. Those parts needing no maintenance have to be removed first to vacate the space to remove those parts needing maintenance. Around electronic control components, there is no space and this will influence heat dissipation. Insufficient heat dissipation will cause electronic parts and components to reduce in performance and even fail. As a result, the reliability, stability of system is seriously influenced.